Device comprising an electric discharge tube



July 3 1956 E. G. DQRGELO 2,753,482

DEVICE COMPRISING AN ELECTRIC DISCHARGE TUBE Filed Oct. l5 1951 mvp 8000 M INVENTOR r/arduyrgel Agenr Educ United States Patent() DEVICE CMPRISING AN ELECTRIC DISCHARGE TUBE Eduard Gerardus Dorgelo, Eindhoven, Netherlands, as-

siguor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application October 15, 1951, Serial No. 251,262

Claims priority, application Netherlands November 22, 1950 4l Claims. (Cl. 315-6) This invention is concerned with devices comprising a high-frequency electric discharge tube of the inductive-output type, i. e. a tube in which an intensity-modulated electron beam produced for example with the aid of a cathode and a control grid, is fed at high speed along an inductive absorption-system and is then collected on a collecting electrode.

In the known tubes of this type the inductive outputsystem is formed by a single rotationally symmetrical cavity resonator having an aperture for the passage of the electron beam at the centre of its front entry and rear exit walls. The cavity resonator may be arranged either within or outside the tube envelope and an electrode at high potential may be arranged within the tube on either side of the cavity resonator.

Although the known devices incorporating inductiveoutput tubes enable an adequate output to be obtained at wavelengths of about 1 meter, it is difficult at smaller wavelengths to produce suciently high energy without the alternating voltage at the cavity resonator assuming an undesirably high value.

The invention has for its object to remove or reduce this diculty. In a device according to the invention comprising an electric discharge tube of the type specified, the inductive absorption-system in constituted, by a plurality of identical cavity resonators which are substantially ilat and are arranged in succession in the direction of movement of the electron beam, the apertures in the front and rear walls being aligned and all the front walls and all the rear walls of the various cavity resonators being respectively interconnected by short conductors, which are secured to the walls adjacent the apertures for the passage of the electron beam. The transit time of the electrons in the beam from the front wall of one cavity resonator to the front wall of the next cavity resonator is preferably equal to about a whole period of the natural frequency of the cavity resonators.

In order that the invention may be more clearly understood and readily carried into effect it will now be described more fully with reference to the accompanying drawing, which shows one form of electric discharge tubes for use in a device according to the invention.

Referring to the single figure of the drawing, 1 designates a cylindrical metal tube sealed, with the aid of a flange, to a short glass cylinder 2; a metal disc 4 is sealed between this cylinder 2 and a hood-shaped glass part 3. The control grid 5 is secured to a conical extension of the disc 4. The glass hood 3 has sealed in it a hollow conductor 6 to which the cathode body 7 is secured. The heater for the cathode and its supply leads may be introduced through the hollow conductor 6, it being possible for the vacuum seal to be formed either adjacent the end of the conductor 6 which is external of the tube as shown or near the cathode body 7. Arranged inside the metal cylinder 1 and in good thermal contact therewith there are three cavity resonaice tors 3, 9 and 10, whose front walls 11, 12 and 13 are connected adjacent the central beam-apertures by a conductor 17, the rear walls 14, 15 and 16 being similarly connected by a conductor 18. The resonators have the shape of cylinders with substantially flat ends. The front wall of the first cavity resonator 8 carries a grid 19. During operation of the tube the metal cylinder is earthed and the cathode acquires a negative voltage of about 800() volts relative to earth. lf the natural frequency of each cavity resonator corresponds to a Wavelength of about cms., the spacing between the front walls 11 and 12 or 12 and 13 respectively may be about 5 cm., said distance being traversed by the electrons in the beam in about one whole period of the natural frequency. After passing through the last cavity resonator the electrons are collected on the bottom 20 of the cylinder 1, which is provided with a, for example, graphite coating 21 for reducing secondary emission. A coupling loop 21 is passed with the aid of a glass plug 22, through the tube wall into the central cavity-resonator 9, these elements together with the other resonators serving as an output system.

What l claim is:

1. An electron discharge device of the inductive output type comprising a cathode, a control electrode and an output system comprising a plurality of rotationally symmetrical cavity resonators each having a forward and rear wall having centrally aligned apertures for the passage of an electron beam and successively positioned in the path of the electron beam, a rst conductor connecting together only the forward walls of the cavity resonators adjacent the aperture therein for the passage of the electron beam, and a second conductor connecting together only the rear walls of the cavity resonators adjacent the aperture therein.

2. An electron discharge device of the .inductive output type comprising a cathode, a control electrode and an output system comprising a plurality of rotationally symmetrical cavity resonators each having a forward and rear wall having centrally aligned apertures for the passage of an electron beam and successively positioned in the path of the electron beam, each of said cavity resonators having a dimension parallel to the electron beam at which the transit time of electrons between successive forward walls is about equal to a whole period of the natural frequency of the cavity resonator, a rst conductor connecting together only the forward walls of the cavity resonators adjacent the aperture therein for the passage of the electron beam, and a second conductor connecting together only the rear walis of the cavity resonators adjacent the aperture therein.

3. An electron discharge device of the inductive output type comprising an envelope having a metallic portion, a cathode, a control electrode and an output srstem in intimate thermal contact with said. metallic por tion of said envelop and comprising a plurality of tationally symmetrical cavity resonators each having a forward and rear wall having centrally aligned apertures for the passage of an electron beam and successively positioned in the path of the electron beam, a rst conductor connecting together only the forward walls of the cavity resonators adjacent the aperture therein for the passage of the electron beam, and a ses ond conductor connecting together only the rear walls of the cavity resonators adjacent the aperture therein.

4. An electron discharge device of the inductive out put type comprising an envelope having a metallic portion, a cathode, a control electrode, and an output system in intimate thermal contact with said metallic envelope portion and comprising a plurality of rotationally symmetrical cavity resonators each having a forward and rear Wall having centrally aligned apertures for the passage of an electron beam and successively positioned in the path of the electron beam, each of said cavity resonators having a dimension parallel to the electron beam at which the transit time of electrons between successive forward walls is about equal to a Whole period of the natural frequency of the resonator, a coupling loop being provided in one of said resonators and extending through said envelope and being accessible to the outside, a rst conductor connecting together only the forward Walls of the cavity resonators adjacent the aperture therein for the passage of the electron beam, and a second conductor connecting together only the rear walls of the cavity resonators adjacent the` aperture therein.

References Cited in the le of this patent UNITED STATES PATENTS FOREIGN PATENTS France Sept. 20, 

